Front running is a crime when done by brokers against their clients (client order comes in, they buy before the client, pushing the price up). There's no law against recommending something you're in already, or selling when you feel like it. Like trading on unknown/insider information (which is not illegal at all except for specific situations - a duty must be owed), the law isn't actually that broad.
One of his months actually has his symbols traded - a bunch of ultra low market cap pennies. DFFN for example has a $19 million market cap.
If you were going to buy ahead of and then sell into 1000 subscribers, these are the stocks in which you'd do it.